1. Field of the Invention
The present invention relates generally to light transmitters and more particularly to an improved interlock for a laser transmitter adapted to be coupled to a fiber-optic transmission line.
2. Description of the Related Art
A transmitter for coupling a modulated light signal to a fiber-optic transmission line, particularly one using a laser light source, produces a narrow cone of light at the exit of the transmitter. Legal requirements relating to external radiation when a fiber-optic coupler is disconnected, such as the CDRH and IEC-825 laser safety requirements, have been an obstacle to using lasers with serial fiber-optic data channels. The following proposals have been made in the prior art to prevent external radiation when a fiber-optic coupler is disconnected.
IBM Technical Disclosure Bulletin, Vol. 22, No. 6, pp. 2393-94 (November, 1979), entitled "Safety Closure for Fiber-Optic Devices", discloses a mechanical closure which prevents external radiation when the coupler is disconnected.
U.S. Pat. Nos. 4,242,657 and 2,573,920 disclose connectors that employ magnets to achieve an interlocking action. Both patents are related to electrical connectors where the absence or presence of the plug will trigger the magnets to either cut off or supply energy to the receptacle. These patents use magnets to physically close the circuit but do not produce a signal external to the connector to indicate proper engagement.
U.S. Pat. No. 3,960,428 discloses an electrical connector in which a signal is generated when the connector is fully engaged. The physical means for actually detecting the presence of the connector is mechanical.
U.S. Pat. No. 4,849,743 discloses a device for electrically detecting that the wires in a connector have been placed in the correct cavity and that they are properly seated.
U.S. Pat. Nos. 4,665,362 and 4,107,604 disclose Hall effect sensors for detecting the relative positions of two members in an assembly. These patents do not disclose either a connector arrangement or an interlocking device.
U.S. Pat. Nos. 4,844,582, 4,690,495 and 4,004,298 show connectors which use magnets in both the plug and receptacle in order to aid in alignment and coupling. U.S. Pat. Nos. 4,844,582 and 4,690,495 disclose fiber-optic connectors.
These prior art proposals have not proved altogether satisfactory, particularly in terms of applicability to transmitters and connectors presently specified for use in commercial applications.